Phase control system for vapor electric converters



Ynected in star.

Patented Aug. 24, 1948 PHASE CONTROL SYSTEM FORI VAPOR ELECTRIC CONVERTERS John P. Ferguson, Berkeley, Calif., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a. corporation of Pennsylvania Application May 23, 1944, Serial No. 536,950

7 Claims. 1

My invention relates to a Vapor-electric device and, particularly, to a phase-shifting transformer for varying the firing instant in a vaporelectric valve. y

In the operation of vapor-electric devices, particularly of the make-alive type, it has hereto-- fore been customary to provide phase-shifting networks including reactors, parallel capacitors, and a series variable reactor for shifting the phase of the excitation potential. The components of the phase-shifting networks are relatively large in dimensions and constructed of scarce and expensive materials.

According to my invention, these phase-shifting networks are replaced by means of a second winding in the primary of each of the supply transformers. My system provides a transformer for each of the impulsing networks, each of the transformers having a plurality oi primary phase windings. These primary phase windings are connected into two groups, one of the groups being connected in polygon. For instance, in the case of a three-phase system, one group of primaries will be connected in delta. The other group of primary windings will be con- For example, in a three-phase system, one group will be connected in Y. These winding groups provide uxes 150 apart, and by varying the current in the respective winding groups, the resultant flux may be shifted over an angle of 40 or 50 without distorting the output potential. y

According to my invention, I provide resistor means for varying the current between the groups so that a single control device may be utilized for shifting the phase in all of the impulsing net- Works.

It is, accordingly, an object of my invention to provide a simplied phase-shifting device for controlling the excitation impulses to a vaporelectric device.

It is a further object of my invention to provide a simplified phase-shifting transformer.

It is a further object of my invention to provide a single phase shifting adjustment.

Other objects and advantages of my invention will be apparent from the following detailed description taken in conjunction with the accompanying drawing, in which the single iigure is a schematic illustration of a vapor-electric converter embodying my invention.

In the exemplary embodiment of my invention, an alternating-current circuit I is connected to a direct-current circuit II by means of a converter transformer I2, and the flow of current between the circuits is controlled by a plurality of vapor-electric valves. For purposes of illustration, I have shown six valves IA to EA connected to the terminals I to 6 of a double threephase transformer. Preferably the transformer I2 is connected to the alternating-current circuit I0 through a suitable circuit breaker 52, while a protective circuit breaker I2 is provided in the direct-current circuit II. Each of the valves of the converter comprises a main anode I4, a vaporizable reconstructing cathode I5 of suitable material, such as mercury, and an excitation electrode I6, herein illustrated as of the makealive type. A grid I3 may be applied if desired.

Excitation impulses are supplied to the excitation electrodes I6 by means of impulsing networks Il, herein illustrated as of the reactor wave distorting type in which a control potential supplied from any suitable source, such as a transformer IB connected to the alternating-current circuit I0, supplies charging potential to a capacitor I9 which then discharges through a saturable reactor 20 to provide a r-ing impulse which is supplied to one or the other of a pair of valves la-a, 2a-Y-5a, 3a--6a by means of a polarity selective network, herein illustrated as a unidirectional conductor 2| in series with each of the make-alive electrodes I6 `and a second unidirectional conductor 22 in shunt with the rst-mentioned unidirectional conductor 2| and the make-alive electrode I 6.

As is customary, each of the impulsing networks is provided with current through a single phase transformer 25. I have provided each of these supply transformers 25 with a plurality of primary windings 2 6 and '21. ings as 2B, on each of the single phase transformers 25 is connected into a polyphase polygonconnected group. This polygon-connected group is supplied with potential from the source, herein the terminals of the control transformer I8. The other winding 21 on each of the supply transformers 25 is connected into a star-connected group with the mid-'point 28 of the star connected to the mid-point 29 of the control transformer I8.

In order to shift the phase, I have provided resistors 30 in each of the leads of the polygonconnected group and a separate resistor 3I in the star lead of the star-connected group. By varying these resistors, the proportion of current flowing in the separate groups may be controlled, thus shifting the resultant ux in the transformers 25 and the phase of the potential applied to the impulsing network I'I. For simplicity, I prefer to provide each of the resistors with a common con- One of the windcations 'can be made therein without departing from the true spirit of my invention or the scope of the appended claims.

I claim as my invention:

1. In a control system for a converter having a plurality of pairs of alternately@conducting valves, and a control circuit' for "each` pair (of valves, a phase controller comprising 'a "source 'of polyphase control potential, agrneutral'connection in said source of control potential, a coupling transformer between said source of control po'- 4tential and each of said control circuits, two pri- :maryv windings on each `of said coupling trans-- oriners, one primarywinding on each coupling transformer being connected in a polygon-'connected group to the sourc'evof control potential, the otherprimary winding of each coupling transformer being connected -in star to -thes'ource o"f control potential, the star point. of said'star-connec'ted group being connected'to-t'he neutral connectionfoffsaidsource of control potential, and adjustable impedance means for controlling the current flow in each'group-'of primary windings.

I" 2t Acontrol system for an electric current converter,having a plurality-of ,pairs of V.alternately conducting electric valves and an impulsing circuit' for each pair ofA valves, comprising a polyph'ase supply circuit having a neutral connection, a substantially independent transformer foreach of-'saidf impulsing networks, twoprimary Wind-- ings lfor' each of said transformers, .meansffor connectingon'e of said primary windings on each of said vtransforr'ners to said-polyphase vsource as ai--istar-conneeted group,'me'ans Ifor connecting the others of said primary windings to'saidI source as a-polygonconnected group; andmeans lfor controlling current flowxto `veach' of said groups.l l` 3. 'In' a control systemffor avap'or `ele'ctric'converter, fhaving a plurality of vpairs rfelectric valves and an' impulsing network lfor each pair of "valves, aphaseshifter for=saidi ini-pulsing Anetworks comprising a polyphase7 supply -circuit havring a neutral connection, a substantially'independent transformer lfor leach "of fsaidJimpulsi-ng networks, twovv primary vwindings ifor each 'of s'a-id transformers, means for connecting :one yofzfsaid primary windings` on each offsaidttransformers to'said. polyphase source Yas= a star-'connected group; means for connecting the othersV of said primary windings toi. saidfso'urce -as a'ipolygonconnected group, and'resis-t'ance means foryaryingthe division yoffcurrent owrto eachrfof said', groups.

4.- Aiphase-'shifting networkxzo'r'nprisi'ng a poly'- p'hase supply circuit, 'a pluralitysof.sirgleephase load-circuits'y a star-'connectedwindingaenergized from saidv supply circuit;l atransf'orrner for each' of'J-'salid load circuits, .each oilsaid transformers including a pair-'of primary windings; one primary win-ding of. veach'- of said transformersfbeing connected in a polygon-connected group, the other primary windings of said transformers being connected in a star-connected group, both of said groups of windings being connected to said starconnected Winding, and means for controlling division of current between said winding groups.

*5. In a control crcuit'for a current'converting system having a plurality-of` .pairsof alternately conducting valves and an impulsing circuit for =l0f eaph pair of valves, a phase shifter comprising ,v-.a transformerior `each of the impulsing circuits, Aeachfoiifsaiol transformers including a winding connected to an impulsing circuit, a plurality 7rof,ipr'ii'irarywindings; a-source of polyphase control 'pot'eirtialrcircuitfmeans for connecting one pri- `Lmary lwinding 'of'each transformer to said source inzpolygon, 'circuitgneans for connecting the other of said ,primary windings of each transformer to fsaidls'ouice in star, and means for varying the ratio of current in said primary windings to `control the phase angle` of the potentialsupplied-to the-impulsing circuits.

6.r In a' control system for `a vapor electric con# verter having a plurality of pairs ofalternately conducting valves, a control circuit vfor-each pair offvalvespconneotions including a neutral 'terminal for supplying polyphase control potential, a coupling transformerb'etween said connections and each of said control circuits, twoprimary windings on each of said couplingv transforml ers, one primary winding on eachcoupling trans= former `being connected in a polygon connected group to the connectionsfor supplying-control potentiaL the other .primary windin'g of-ea'ch coupling transformer'being connected` in star to the connections for supplying control .potential, the star point of said star-connected'group-being connected to the neutral terminal of said kconnections for supplying control potential, `and ade 40 justable impedance means 'for icontrollingythe current ow in eachl group-of primarywindin'gs.

7. In a control system for-ia poly-phase cone verter having a plurality vof'pairs of alternately conductingy valves and an impulsing circuit for each pair of valves,` a phase controllerrfor said impulsing circuits comprisinga-.polyphase supply circuit, a lstar-connecited Winding energizedv from saidfsupply circuit'a tra'nsformeroreach-of aid impulsing circuits, each of :said-transformers'including.' a .-pairf of primaryrwinding's, Ione winding. of^ea`ch :of fsaid transformers being `connected.in a polygon-connected group, the other --prifmar'y windings iof .said transformers beinglconneote'din a1 'star-connected group, both lotI .said -1 groups'zfof windings abeingconnected 'to ,said istareconnected Winding,- and me'an's'-e for controlling* division y'of current between said winding groups.

.1 JOHN Eli-FERGUSON.

REFERENCES CITED The following references are of lrecord Viii-the leof this patent:

.UNITED STATES PATENTS 

